The invention relates to a method and apparatus for engaging an object within a well bore. More particularly, but not by way of limitation, the invention relates to a method and apparatus for mechanically latching unto an object, and thereafter, selectively locking and unlocking the apparatus for manipulation by the operator.
In the development of oil and gas fields, well bores are drilled through subterranean reservoirs. Ultimately, a well will be completed to a hydrocarbon bearing reservoir, as will be understood by those of ordinary skill in the art. Afterwards, the hydrocarbon bearing reservoir is produced, and the hydrocarbons are ultimately refined.
The well bores are generally of small diameter and many times are highly deviated. The forces necessary to drill these well bores are significant. Many times, tools become lodged within the well bore due to operational problems associated with drilling and completing wells, particularly in highly deviated, extended reach wells.
In order to retrieve these tools (sometimes referred to by those of ordinary skill in the art as a "fish"), a work string is employed that has attached thereto a retrieving tool. Once the retrieving tool is latched onto the fish, the operator will begin operations to dislodge the tool. The operation may include jarring of the fish in order to dislodge. The procedure may also include pumping of a fluid through the inner diameter of the work string and the inner diameter of the retrieving in the tool in order to aid in the retrieval of the fish. Reverse circulation about the down hole tools is also possible.
During the procedure, the operator may find it desirable and/or necessary to unlatch the retrieving tool from the fish. Also, the operator may wish to continuously pump through the retrieving tool. As those of ordinary skill in the art will appreciate, the retrieval process requires adaptation to many different circumstances. While there have been developed over the years various down hole tools for latching and retrieving down hole tools, they all suffer from several deficiencies. For instance, the prior art retrieving tools suffer from the inability to remain latched during pumping operations due to the sensitivity of the releasing mechanism to fluid pumping. Also, the prior art designs suffer from being structurally infirm. Moreover, the prior art designs can not be latched, and unlatched, multiple times with a significant degree of confidence.
Therefore, there is a need for a method and apparatus that will allow for the dependable latching and unlatching of a down hole retrieving apparatus. There is also a need for a retrieving tool that is designed for pump through application without the possibility of premature release. Further, there is a need for a retrieving tool wherein the latching and unlatching is dependable.